GUGC had this over 10 years ago (Score 1)

GUGC (Griffith University Gold Coast) had a similar thing in place 10 years ago. It was used for COBOL assignments, but could be adapted to other languages. It compared literal blocks of text, parse trees, variable names etc. I'm pretty sure Colin Thorne wrote it. You could take a program, cut it into sections, remname large chunks, move things around and it would assign a correlation with other works in the class.

You could then set 'honeypots' up and see if there was a pattern of collusion or plagiarism.